1) Field of the Invention
The present invention relates to a communication system, a communication method, a communication apparatus, and a computer product to establish communications between a plurality of devices connected to a network.
2) Description of the Related Art
Devices such as printers and scanners can be connected to a network, and thus printers or the like can be operated from personal computers (PCs) connected to a network such as local area network (LAN). In such an environment, for example, a user who first visits an office wishes to output a document stored in a laptop PC carried in the office through a printer installed in the office. In this case, the document is copied to a Floppy® disc, and the Floppy® disc is inserted into another PC connected to the network to which the printer is connected. The document is then printed by a process on the PC.
Recently, however, wireless LAN is common in use, and as long as authentication for security of the wireless LAN is permitted, users can easily access a network at any locations.
Service location protocol (SLP), Jini, and the like are known as technologies for searching peripheral devices present on a network or service contents provided by the peripheral devices and automatically setting necessary devices through mobile terminals such as PCs and personal digital assistants (PDAs).
In the SLP and Jini, devices that centrally control service information called as Directory Agent and Lookup Table are determined. Each of the devices registers service information in a central control device, and service search side inquires the central control device with one-on-one communication by unicast.
These technical standards, however, cause a problem that it is difficult to determine places where devices that relate with devices and services found on a network are actually installed.
As a technique that solves this problem, a method of physically specifying a device on the other side using a second communication unit such as Infrared Data Association (IrDA) or the like is known. In this method, however, both terminals which make communication therebetween should have the second communication unit such as IrDA, and thus the cost is high and versatility is low.
As a technique that solves this problem, a method of specifying a communication address of a desired device on the other side so as to establish communication with the other device is known (see, for example, Japanese Patent Application Laid-open No. 2001-154822).
In the method of establishing communication with the other device, common search keys are input into two devices between which the communication is established and the communication is established between the two devices under the condition in which these key are identical to each other. When, for example, the input of the search key is failed, there may be inconveniences such as the procedure has to return to the starting point. Further, a printer which belongs to a different subnet cannot be found. It is, therefore, desired to provide a method of being capable of specifying a place where a device that relates with a device or a service found on a network is actually installed, maintaining a higher security level, and efficiently specifying an address or the like of the device of a communication destination.